The game of golf is one of the most popular recreational sports in the world in terms of participants. The popularity of golf does not mean that the game is easy. Golf requires consistent precision of movement to achieve mastery of the game. Subtle imperfections in the execution of strokes produce amplified errors in the outcome of the shot.
Being able to putt in a technically correct manner is of vital importance to all golfers from the high handicap, weekend club player to the professional, as putting is where most strokes are dropped during a round. This is acknowledged in one of the most commonly used phrases on the golf course, “drive for show, putt for dough”. Putting is also one of the hardest aspects of the game to master. There are four main technical inaccuracies that are common among players. These inaccuracies cause inconsistent swings and hence missed putts.                1. Professionals cite rotation of the wrists during back swing, the transition from back swing to forward swing, or forward swing resulting in rotation of the club in a direction axial to the vertical axis as the primary reason for inaccurate putting strokes. The club head should remain perpendicular to the intended line of travel of the ball during the backstroke.        2. Another reason for inaccurate putting is due to deviation of the club head from the intended line of the putt. The putter should trace a straight line from the start of the back swing, through to the transition from back swing to forward swing and back through the forward swing to contact with the ball.        3. A further reason cited for inaccurate putts is due to accelerating too quickly during back swing and/or forward swing. Ideally, smooth acceleration and deceleration should be achieved at all times during back swing, forward swing and the transition between the two.        4. Rotation of the club head in a direction axial to the intended line of travel of the ball is a further technical inaccuracy in player's putting strokes. The club head should remain approximately parallel with the horizontal plane at all times during the stroke.        
Most players generally seek the services of a professional to detect inaccuracies in their putting stroke and to correct them. A player then needs to practice these corrected putting techniques and implement the advice received through repetitive practice. Not only is this method of putting swing correction expensive, it is also often ineffective. When the player is practising the correct stroke, without supervision from their coach, bad habits tend to creep back into their action and the player spends his or her time practicing a technically incorrect stroke.
A more convenient and cost effective solution is for the player to use a device that monitors his stroke during practice and alerts them when a stroke is technically inaccurate. In this way, a player can repetitively practice a correct stroke and mirror it during a game.
There is a large body of prior art that attempts to address the above problem. U.S. Pat. No. 4,930,787 (the '787 patent), in the name of Nobles, discloses a device for attachment to a putter which produces a signal during a puffing stroke if the longitudinal axis of the putter head is rotated out of parallel with the horizontal plane or when the putter head undergoes any clockwise or counter clockwise rotation on the backstroke.
The putting trainer of the '787 patent is designed to be fixed, by means of screws or other fastening means, to the backside of the putter. Hence, a player using this device requires a special training putter to fix the device. It is probable that this putter would have different weight and balance characteristics to a putter the golfer would use during a game. It should be appreciated that it is of greater benefit to practice with a putter that will be used during a game and hence the device of the '787 patent does not effectively address the problems listed above.
Furthermore, the device of the '787 patent does not address the path deviation problem, as mentioned above. Thus, the club head can trace any path during the back swing and no stroke error will be indicated. Hence, the device disclosed in the '787 patent, is deficient in solving the problems of putting stroke inaccuracies as discussed above.
U.S. Pat. No. 5,435,561 (the '561 patent), in the name of Conley, discloses and claims a putting stroke training device comprising an inertial sensor for detecting movement in a direction parallel to the plane of the club face and rotation of the club head in a direction axial to the longitudinal axis of the shaft during putting. The sensor includes an elongated arm mounted on a pivot point which is orientated in a direction perpendicular both to the longitudinal axis of the shaft of the club and also to the plane of the club face.
The design of the device of the '561 patent necessitates that it be installed within the shaft of a putter. This is an obvious deficiency of the device as again, a player must practice with one club with the device installed, and play with a separate club. Hence, as the practice club and playing club will no doubt have different balance points and characteristics, the benefits of putting practice using this device and a practice putter are lost.
U.S. Pat. No. 5,441,269 (the '269 patent), in the name of Henwood, discloses a putting stroke training device that detects when the putter head has accelerated or decelerated too quickly, as in technical inaccuracy 3 described above, and also when the putter head is rotated axially around the vertical axis at the moment of contact between the ball and the club head. This device uses a pendulum actuator and an impact actuator to sense technical faults in the putting stroke.
The device of the '269 patent does not adequately address the problems of stroke inaccuracy as it measures only axial rotation of the club head around the vertical axis at the moment of contact. Hence, a player may execute a stroke that causes the club to rotate axially around the vertical axis during back swing, but may correct this inaccuracy during forward swing before contact that would not be considered a technically correct stroke but the device disclosed in the '269 patent would give no indication to the player of the stroke error.
Furthermore, the device of the '269 patent must be either installed within a cavity in a hollow club head, or secured on top of a club head by means of screws or similar fastening devices. Hence, it also requires practicing putting strokes using a putter that would not be used during play. There is minimal benefit in practicing with a putter having different characteristics to that of a putter used during a game.
Hence, there remains the need for a device for detecting inaccuracies in putting strokes such as those listed above. Furthermore, this device must be capable of being easily attached and unattached to a player's putter so that the same club can be used by a player in practice and in games. The advantage of such a device is that a player can detect and correct technical inaccuracies in their putting stroke and play a round of golf using the same club that has been used to practice shots correctly.